High-stretchable high-sensitive flexible force-sensitive sensing fiber and preparation method therefor

ABSTRACT

A high-stretchable high-sensitive flexible force-sensitive sensing fiber and a preparation method therefor comprising the specific preparation method is as follows: uniformly and synergistically dispersing a one-dimensional (1D) nanowire/nanotube and a two-dimensional (2D) conductive sheet layer in a thermoplastic elastomer solution; formulating a uniform dispersion solution of a certain concentration; and using a wet spinning process to prepare an elastic composite fiber with a highly oriented 1D/2D hybrid network. The above-described composite fiber is placed in a metal precursor solution to fully swell, and then placed in reductive steam for reduction, to reduce metal precursors to zero-dimensional (0D) metal nanoparticles, thereby preparing a flexible force-sensitive sensing fiber based on a 0D/1D/2D three-dimensional collaborative network.

BACKGROUND Technical Field

The present invention relates to the field of force-sensitive sensing fibers, and more particularly, to a high-stretchable high-sensitive flexible force-sensitive sensing fiber and a preparation method therefor.

Description of Related Art

A flexible force-sensitive sensing material is a flexible conductive composite material used to sense a surface force of a material. The material is formed by compounding a polymer matrix (or a flexible matrix, including rubber, a plastic film, a fiber fabric, etc.) having a better flexibility with a conductive filler in a certain manner. Under the action of an external force, the material is elastically deformed, a conductive network in the matrix is reconstructed, a corresponding response is shown in an electrical performance, and force-sensitive sensing may be implemented by capturing qualitative and quantitative relations between the electrical performance and the external force or deformation. Since the material may be attached to various irregular surfaces and has advantages of being flexible, stretchable, light and portable, the material has a wide application prospect in fields such as wearable device, intelligent robot, electronic skin, medical detection, and becomes a hot research direction of electronic materials.

However, due to the easy agglomeration of the conductive fillers in a traditional blending and compounding processing method, the prepared conductive composite material is often poor in flexibility, thus losing the use value. However, in most of the current solutions, a one-dimensional nano-material carbon nanotube or silver nanowire with a high conductivity and a high diameter-length ratio is added into elastomers such as silicone rubber and polyurethane, and the conductive network formed by a one-dimensional nano-material is used, thus greatly reducing an amount of filler to ensure the flexibility and the high conductivity of the material. However, a single filler still has great deficiencies in reducing the amount of filler, and the preparation of a high-stretchable high-sensitive force-sensitive sensing material is still an important problem that needs to be solved urgently.

In addition, a flexible force-sensitive sensing fiber has a wider wearable prospect compared with traditional two-dimensional and three-dimensional sensing materials due to advantages such as light weight, easy processing and capability of meeting the requirements of spinning and weaving. Therefore, the preparation of the high-stretchable high-sensitive flexible force-sensitive sensing fiber has more important practical significance.

SUMMARY

The present invention aims at solving the problem that the current flexible force-sensitive sensing material cannot be well applied due to poor stretchability and low sensitivity, and provides a high-stretchable high-sensitive flexible force-sensitive sensing fiber based on a 0D/1D/2D three-dimensional collaborative network and a preparation method therefor, which not only well solves the problems of poor stretchability, low sensitivity and the like of the force-sensitive sensing material, but also endows the material with spinnable and weavable characteristics and provides further support for practical application of the material.

In order to achieve the above objective, the following technical solutions are used in the present invention.

A preparation method for a high-stretchable high-sensitive flexible force-sensitive sensing fiber includes the following steps:

1) preparing a synergistic dispersion solution of a one-dimensional nanowire/nanotube and a two-dimensional nanosheet filler firstly, and then dissolving a thermoplastic elastomer in the synergistic dispersion solution to obtain a polymer solution with stably dispersed fillers;

2) spinning the polymer solution obtained in the step 1) by solution spinning to obtain a composite fiber with a certain thickness;

3) placing the composite fiber obtained in the step 2) into a metal precursor solution to fully swell, metal ions being diffused among molecular chains during swelling, and after the composite fiber is completely swelled, fully reducing the fiber with reductive steam to reduce the metal ions into nanoparticles; and

4) washing redundant metal nanoparticles attached to a surface of the fiber with water to obtain the high-stretchable high-sensitive flexible force-sensitive sensing fiber.

Preferably, the one-dimensional nanowire/nanotube mentioned in the step 1) is one of a silver nanowire, a gold nanowire, a copper nanowire, a copper-silver core-shell nanowire, a single-walled carbon nanotube, a less-walled carbon nanotube and a multi-walled carbon nanotube.

Preferably, the two-dimensional nanosheet mentioned in the step 1) is one of single-layer graphene, few-layer graphene, a gold nanosheet and a silver nanosheet.

Preferably, a mass ratio of the one-dimensional nanowire/nanotube to the two-dimensional nanosheet in the step 1) is 10:1 to 1:10.

Preferably, a total mass of the one-dimensional nanowire/nanotube and the two-dimensional nanosheet filler mentioned in the step 1) accounts for 0.1% to 5% of a mass of the thermoplastic elastomer.

Preferably, the thermoplastic elastomer mentioned in the step 1) is selected from one of thermoplastic polyurethane (TPU), a thermoplastic polystyrene-butadiene-styrene triblock copolymer (SBS), and a polystyrene-ethylene-butylene-styrene triblock copolymer (SEBS).

Preferably, a mass of the thermoplastic elastomer mentioned in the step 1) accounts for 5% to 30% of a total mass of the polymer solution.

Preferably, a diameter of a cross-section of the composite fiber mentioned in the step 2) is 50 μm to 300 μm.

Preferably, metal in the metal precursor solution mentioned in the step 3) is selected from one of copper, silver and gold.

Preferably, a concentration of the metal precursor solution mentioned in the step 3) is 5 wt % to 30 wt %.

Preferably, the swelling mentioned in the step 3) lasts for more than 2 hours.

Preferably, the reductive steam mentioned in the step 3) is one of hydrazine hydrate steam and hydroiodic acid steam.

Preferably, a concentration of the reductive steam mentioned in the step 3) is 1 g/m³ to 10 g/m³.

Preferably, the reducing with the reductive steam mentioned in the step 3) has a temperature of 70° C. to 100° C., and lasts for 5 minutes to 1 hour.

A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method above, the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than 20.

Compared with the prior art, the present invention has the following advantages and technical effects.

1) The construction of the 0D/1D/2D three-dimensional collaborative network enables multi-dimensional fillers to be in bridge connection with each other when the force-sensitive sensing fiber according to the present invention is stretched, and a collaborative effect ensures the high stretchability of the force-sensitive sensing fiber (the tensile strength is more than 500%). A quick response of a multi-dimensional filler joint during stretching also ensures the high sensitivity of the material (the sensitivity can reach more than 50).

2) Very few 1D/2D conductive fillers are arranged, which cannot affect the flexibility of the material, and a method of swelling adsorption—in-situ reduction is used in the introduction of 0D metal nanoparticles, so as to exist only at a certain depth on the surface of the material and have very little damage to the flexibility of the material, thus ensuring that the material still has good stability after repeated stretching and recovery for more than 10000 times.

3) The prepared force-sensitive sensing material is a one-dimensional elastic fiber, which not only is more fine and convenient to carry, but also can be processed into various shapes, for example, preparing two-dimensional electronic fabrics through weaving, and meanwhile, the fiber has excellent skin adhesion and air permeability, so that the fiber has a wide application prospect in terms of intelligent wearable device and flexible electronic skin.

4) After the material is naturally cooled, the material is grinded to obtain a black powdery material.

DESCRIPTION OF THE EMBODIMENTS

The present invention is further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the embodiments.

Stretchability of a fiber is obtained by measuring a difference between a stretched length and an initial length and then dividing the difference by the initial length. A gauge factor of fiber stretching is calculated by the formula GF=(ΔR/R₀)/(ΔL/L₀), wherein R₀ is an initial fiber resistance and L₀ is an initial length value; and ΔR is corresponding change in resistance and ΔL is corresponding change in length.

Embodiment 1

1) 45 mg of single-walled carbon nanotube (CNT) and 4.5 mg of single-layer graphene (GE) were added into 90 g of dimethylformamide (DMF) and ultrasonically dispersed at a constant temperature of 25° C.; after 30 minutes, 10 g of SBS was added into a dispersion and stirred at 50° C. for 10 minutes, after the SBS was completely dissolved, the mixture was cooled to 25° C. and then ultrasonically dispersed for 30 min continuously to prepare a 10 wt % SBS solution stably dispersed on the basis of a hybrid network.

2) Under an ambient temperature, a polyvinyl alcohol (PVA) aqueous solution (with a concentration of 10 wt %) was used as a coagulating bath to prepare a SBS composite fiber with a diameter of 200 μm by a wet spinning process. The SBS composite fiber was swelled in an ethanol solution (15 wt %) of silver trifluoroacetate (AgCOOF₃) for 5 hours, and then the swelled sample was placed in hydrazine hydrate steam (with a concentration of 5 g/m³) for reduction at 80° C. for 30 minutes.

3) After the sample was completely reduced, the sample was repeatedly washed with deionized water to remove hydrazine hydrate and attached silver nanoparticles on the surface to prepare a flexible force-sensitive sensing fiber with a stretchability of 550% and a sensitivity of 253.

Embodiment 2a

1) 4.5 mg of single-walled carbon nanotube (CNT) and 45 mg of single-layer graphene (GE) were added into 90 g of dimethylformamide (DMF) and ultrasonically dispersed at a constant temperature of 25° C.; after 30 minutes, 10 g of SBS was added into a dispersion and stirred at 50° C. for 10 minutes, after the SBS was completely dissolved, the mixture was cooled to 25° C. and then ultrasonically dispersed for 30 min continuously to prepare a 10 wt % SBS solution stably dispersed on the basis of a hybrid network.

2) Under an ambient temperature, a polyvinyl alcohol (PVA) aqueous solution (with a concentration of 10 wt %) was used as a coagulating bath to prepare a SBS composite fiber with a diameter of 200 μm by a wet spinning process, the SBS composite fiber was swelled in an ethanol solution (15 wt %) of copper trifluoroacetate (Cu(COOF₃)₂) for 5 hours, and then the swelled sample was placed in hydrazine hydrate steam (with a concentration of 5 g/m³) for reduction at 80° C. for 30 minutes.

3) After the sample was completely reduced, the sample was repeatedly washed with deionized water to remove hydrazine hydrate and attached silver nanoparticles on the surface to prepare a flexible force-sensitive sensing fiber with a stretchability of 550% and a sensitivity of 270.

Embodiment 3

1) 250 mg of single-walled carbon nanotube (CNT) and 250 mg of single-layer graphene (GE) were added into 90 g of dimethylformamide (DMF) and ultrasonically dispersed at a constant temperature of 25° C.; after 30 minutes, 10 g of SBS was added into a dispersion and stirred at 50° C. for 10 minutes, after the SBS was completely dissolved, the mixture was cooled to 25° C. and then ultrasonically dispersed for 30 minutes continuously to prepare a 10 wt % SBS solution stably dispersed on the basis of a hybrid network.

2) Under an ambient temperature, a polyvinyl alcohol (PVA) aqueous solution (with a concentration of 10 wt %) was used as a coagulating bath to prepare a SBS composite fiber with a diameter of 200 μm by a wet spinning process, the SBS composite fiber was swelled in an ethanol solution (15 wt %) of silver trifluoroacetate (AgCOOF₃) for 5 hours, and then the swelled sample was placed in hydroiodic acid steam (with a concentration of 5 g/m³) for reduction at 80° C. for 30 minutes.

3) After the sample was completely reduced, the sample was repeatedly washed with deionized water to remove hydroiodic acid and attached silver nanoparticles on the surface, thus preparing a flexible force-sensitive sensing fiber with a stretchability of 500% and a sensitivity of 100.

Embodiment 4

1) 5 mg of single-walled carbon nanotube (CNT) and 5 mg of single-layer graphene (GE) were added into 90 g of dimethylformamide (DMF) and ultrasonically dispersed at a constant temperature of 25° C.; after 30 minutes, 10 g of SBS was added into a dispersion and stirred at 50° C. for 10 minutes, after the SBS was completely dissolved, the mixture was cooled to 25° C. and then ultrasonically dispersed for 30 min continuously to prepare a 10 wt % SBS solution stably dispersed on the basis of a hybrid network.

2) Under an ambient temperature, a polyvinyl alcohol (PVA) aqueous solution (with a concentration of 10 wt %) was used as a coagulating bath to prepare a SBS composite fiber with a diameter of 200 μm by a wet spinning process, the SBS composite fiber was swelled in an ethanol solution (15 wt %) of copper trifluoroacetate (Cu(COOF₃)₂) for 5 hours, and then the swelled sample was placed in hydroiodic acid steam (with a concentration of 5 g/m³) for reduction at 80° C. for 30 minutes.

3) After the sample was completely reduced, the sample was repeatedly washed with deionized water to remove hydroiodic acid and attached silver nanoparticles on the surface to prepare a flexible force-sensitive sensing fiber with a stretchability of 700% and a sensitivity of 300. 

1. A preparation method for a high-stretchable high-sensitive flexible force-sensitive sensing fiber, comprising the following steps: 1) preparing a synergistic dispersion solution of a one-dimensional nanowire/nanotube and a two-dimensional nanosheet filler firstly, and then dissolving a thermoplastic elastomer in the synergistic dispersion solution to obtain a polymer solution with stably dispersed fillers; 2) spinning the polymer solution obtained in the step 1) by solution spinning to obtain a composite fiber; 3) placing the composite fiber obtained in the step 2) into a metal precursor solution to fully swell, metal ions being diffused among molecular chains during swelling, and after the composite fiber is completely swelled, fully reducing the composite fiber with reductive steam to reduce the metal ions into metal nanoparticles; and 4) washing redundant metal nanoparticles attached to a surface of the fiber with water to obtain the high-stretchable high-sensitive flexible force-sensitive sensing fiber.
 2. The preparation method for the high-stretchable high-sensitive flexible force-sensitive sensing fiber according to claim 1, wherein the one-dimensional nanowire/nanotube in the step 1) is one of a silver nanowire, a gold nanowire, a copper nanowire, a copper-silver core-shell nanowire, a single-walled carbon nanotube, a less-walled carbon nanotube and a multi-walled carbon nanotube; and the two-dimensional nanosheet is one of single-layer graphene, few-layer graphene, a gold nanosheet and a silver nanosheet.
 3. The preparation method for the high-stretchable high-sensitive flexible force-sensitive sensing fiber according to claim 1, wherein a mass ratio of the one-dimensional nanowire/nanotube to the two-dimensional nanosheet in the step 1) is 10:1 to 1:10; and a total mass of the one-dimensional nanowire/nanotube and the two-dimensional nanosheet filler accounts for 0.1% to 5% of a mass of the thermoplastic elastomer.
 4. The preparation method for the high-stretchable high-sensitive flexible force-sensitive sensing fiber according to claim 1, wherein the thermoplastic elastomer in the step 1) is selected from one of thermoplastic polyurethane, a thermoplastic poly(styrene-butadiene-styrene) triblock copolymer, a poly(styrene-ethylene/butylene-styrene) triblock copolymer; and a mass of the thermoplastic elastomer accounts for 5% to 30% of a total mass of the polymer solution.
 5. The preparation method for the high-stretchable high-sensitive flexible force-sensitive sensing fiber according to claim 1, wherein a diameter of a cross-section of the composite fiber in the step 2) is 50 μm to 300 μm.
 6. The preparation method for the high-stretchable high-sensitive flexible force-sensitive sensing fiber according to claim 1, wherein metal in the metal precursor solution in the step 3) is selected from one of copper, silver and gold; and a concentration of the metal precursor solution is 5 wt % to 30 wt %.
 7. The preparation method for the high-stretchable high-sensitive flexible force-sensitive sensing fiber according to claim 1, wherein time of the swelling in the step 3) lasts for more than 2 hours.
 8. The preparation method for the high-stretchable high-sensitive flexible force-sensitive sensing fiber according to claim 1, wherein the reductive steam in the step 3) is hydrazine hydrate steam or hydroiodic acid steam; and a concentration of the reductive steam is 1 g/m³ to 10 g/m³.
 9. The preparation method for the high-stretchable high-sensitive flexible force-sensitive sensing fiber according to claim 1, wherein the reductive steam in the step 3) has a temperature of 70° C. to 100° C., and lasts for 5 minutes to 1 hour.
 10. A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method according to claim 1, wherein the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than
 20. 11. A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method according to claim 2, wherein the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than
 20. 12. A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method according to claim 3, wherein the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than
 20. 13. A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method according to claim 4, wherein the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than
 20. 14. A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method according to claim 5, wherein the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than
 20. 15. A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method according to claim 6, wherein the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than
 20. 16. A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method according to claim 7, wherein the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than
 20. 17. A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method according to claim 8, wherein the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than
 20. 18. A high-stretchable high-sensitive flexible force-sensitive sensing fiber prepared by the method according to claim 9, wherein the flexible force-sensitive sensing fiber has a tensile strength of more than 500%, and a sensitivity of more than
 20. 